Bisphenols such as bisphenol A (4,4′-isopropylidenephenol) (BPA) are used extensively in plastics and composites due to its aromaticity that provides high mechanical strength to BPA derived polymers. Approximately 6.5 million tons are produced a year globally for the production of thermosets and thermoplastics. Industrially, these polymers are used in the manufacturing of goods such as metal food can epoxy resin linings and polycarbonate containers. BPA is a known endocrine disruptor and is derived from petroleum, a non-renewable resource. Therefore, BPA alternatives with fewer health concerns derived from sustainable renewable alternatives would have an immeasurable impact on the polymer, coatings, adhesives, and additives industries.
In recent studies, low dose exposure to BPA during fetal development and puberty caused lifelong physical and mental health such as birth defects, obesity, thyroid issues, and cause changes in reproductive development, to name a few. As an indication of how much humans are exposed to BPA, it is estimated that over 90% of the population of industrial countries have BPA and its metabolites in their urine. Most recently, studies suggest there may be a link between autism spectrum disorder in children and BPA exposure.
Additionally, currently used industrial bisphenols are derived from petroleum, a non-renewable resource on the time scale of consumption. Utilizing renewable sources of aromaticity, such as lignin, the second most abundant natural polymer rich in aromatic content, holds the potential to be a low cost sustainable alternative to petroleum feedstocks. On average, 70 million tons of lignin is produced as a waste product of the paper and pulping industry. The breakdown of lignin into monophenolics through processes such as pyrolysis is a promising feedstock of functionalized phenols that can be used as is or processed into specialty chemicals.
Successful bisphenol alternatives must provide comparable or improved thermomechanical and optical properties, function as a drop in replacement, and have decreased toxicity and endocrine disruption potential. Many current alternatives provide similar properties but are difficult to synthesize and require expensive processing steps. These intensive synthesis steps limit their application as industrial alternatives to bisphenols. Other alternatives are derived from natural resources; however, these resources cannot sustain the production quotas necessary for industrial production. Furthermore, many other bisphenol alternatives are synthesized from toxic or volatile monomers such as formaldehyde and acetone.
Additionally, many syntheses use electrochemistry, harsh mineral acids, or complex catalyst systems for the synthesis of bisphenol alternatives, which may lead to low yields, damaged processing equipment, and high catalyst cost. Methods and compositions capable of addressing one or more of these issues would be a welcome addition to the state of the art.